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From: Vlastimil Babka <vbabka@suse.cz>
To: Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Vlastimil Babka <vbabka@suse.cz>,
	Kent Overstreet <kent.overstreet@linux.dev>,
	Suren Baghdasaryan <surenb@google.com>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH v2] mm, slab: don't wrap internal functions with alloc_hooks()
Date: Mon, 27 May 2024 11:01:28 +0200
Message-ID: <20240527090127.21979-2-vbabka@suse.cz>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

The functions __kmalloc_noprof(), kmalloc_large_noprof(),
kmalloc_trace_noprof() and their _node variants are all internal to the
implementations of kmalloc_noprof() and kmalloc_node_noprof() and are
only declared in the "public" slab.h and exported so that those
implementations can be static inline and distinguish the build-time
constant size variants. The only other users for some of the internal
functions are slub_kunit and fortify_kunit tests which make very
short-lived allocations.

Therefore we can stop wrapping them with the alloc_hooks() macro.
Instead add a __ prefix to all of them and a comment documenting these
as internal. Also rename __kmalloc_trace() to __kmalloc_cache() which is
more descriptive - it is a variant of __kmalloc() where the exact
kmalloc cache has been already determined.

The usage in fortify_kunit can be removed completely, as the internal
functions should be tested already through kmalloc() tests in the
test variant that passes non-constant allocation size.

Reported-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
v2: keep _noprof per Kent, remove usage from fortify_kunit per Kees

 include/linux/slab.h | 48 ++++++++++++++++++++++----------------------
 lib/fortify_kunit.c  |  5 -----
 lib/slub_kunit.c     |  2 +-
 mm/slub.c            | 26 ++++++++++++------------
 4 files changed, 38 insertions(+), 43 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7247e217e21b..ed6bee5ec2b6 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -528,9 +528,6 @@ static_assert(PAGE_SHIFT <= 20);
 
 #include <linux/alloc_tag.h>
 
-void *__kmalloc_noprof(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
-#define __kmalloc(...)				alloc_hooks(__kmalloc_noprof(__VA_ARGS__))
-
 /**
  * kmem_cache_alloc - Allocate an object
  * @cachep: The cache to allocate from.
@@ -568,31 +565,34 @@ static __always_inline void kfree_bulk(size_t size, void **p)
 	kmem_cache_free_bulk(NULL, size, p);
 }
 
-void *__kmalloc_node_noprof(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
-							 __alloc_size(1);
-#define __kmalloc_node(...)			alloc_hooks(__kmalloc_node_noprof(__VA_ARGS__))
-
 void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t flags,
 				   int node) __assume_slab_alignment __malloc;
 #define kmem_cache_alloc_node(...)	alloc_hooks(kmem_cache_alloc_node_noprof(__VA_ARGS__))
 
-void *kmalloc_trace_noprof(struct kmem_cache *s, gfp_t flags, size_t size)
-		    __assume_kmalloc_alignment __alloc_size(3);
+/*
+ * The following functions are not to be used directly and are intended only
+ * for internal use from kmalloc() and kmalloc_node()
+ * with the exception of kunit tests
+ */
+
+void *__kmalloc_noprof(size_t size, gfp_t flags)
+				__assume_kmalloc_alignment __alloc_size(1);
+
+void *__kmalloc_node_noprof(size_t size, gfp_t flags, int node)
+				__assume_kmalloc_alignment __alloc_size(1);
 
-void *kmalloc_node_trace_noprof(struct kmem_cache *s, gfp_t gfpflags,
-		int node, size_t size) __assume_kmalloc_alignment
-						__alloc_size(4);
-#define kmalloc_trace(...)			alloc_hooks(kmalloc_trace_noprof(__VA_ARGS__))
+void *__kmalloc_cache_noprof(struct kmem_cache *s, gfp_t flags, size_t size)
+				__assume_kmalloc_alignment __alloc_size(3);
 
-#define kmalloc_node_trace(...)			alloc_hooks(kmalloc_node_trace_noprof(__VA_ARGS__))
+void *__kmalloc_cache_node_noprof(struct kmem_cache *s, gfp_t gfpflags,
+				  int node, size_t size)
+				__assume_kmalloc_alignment __alloc_size(4);
 
-void *kmalloc_large_noprof(size_t size, gfp_t flags) __assume_page_alignment
-					      __alloc_size(1);
-#define kmalloc_large(...)			alloc_hooks(kmalloc_large_noprof(__VA_ARGS__))
+void *__kmalloc_large_noprof(size_t size, gfp_t flags)
+				__assume_page_alignment __alloc_size(1);
 
-void *kmalloc_large_node_noprof(size_t size, gfp_t flags, int node) __assume_page_alignment
-							     __alloc_size(1);
-#define kmalloc_large_node(...)			alloc_hooks(kmalloc_large_node_noprof(__VA_ARGS__))
+void *__kmalloc_large_node_noprof(size_t size, gfp_t flags, int node)
+				__assume_page_alignment __alloc_size(1);
 
 /**
  * kmalloc - allocate kernel memory
@@ -654,10 +654,10 @@ static __always_inline __alloc_size(1) void *kmalloc_noprof(size_t size, gfp_t f
 		unsigned int index;
 
 		if (size > KMALLOC_MAX_CACHE_SIZE)
-			return kmalloc_large_noprof(size, flags);
+			return __kmalloc_large_noprof(size, flags);
 
 		index = kmalloc_index(size);
-		return kmalloc_trace_noprof(
+		return __kmalloc_cache_noprof(
 				kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
 				flags, size);
 	}
@@ -671,10 +671,10 @@ static __always_inline __alloc_size(1) void *kmalloc_node_noprof(size_t size, gf
 		unsigned int index;
 
 		if (size > KMALLOC_MAX_CACHE_SIZE)
-			return kmalloc_large_node_noprof(size, flags, node);
+			return __kmalloc_large_node_noprof(size, flags, node);
 
 		index = kmalloc_index(size);
-		return kmalloc_node_trace_noprof(
+		return __kmalloc_cache_node_noprof(
 				kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
 				flags, node, size);
 	}
diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c
index 39da5b3bc649..044f409ef856 100644
--- a/lib/fortify_kunit.c
+++ b/lib/fortify_kunit.c
@@ -233,11 +233,6 @@ static void fortify_test_alloc_size_##allocator##_dynamic(struct kunit *test) \
 		kfree(p));						\
 	checker(expected_size,						\
 		kmalloc_array_node(alloc_size, 1, gfp, NUMA_NO_NODE),	\
-		kfree(p));						\
-	checker(expected_size, __kmalloc(alloc_size, gfp),		\
-		kfree(p));						\
-	checker(expected_size,						\
-		__kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
 		kfree(p));						\
 									\
 	orig = kmalloc(alloc_size, gfp);				\
diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
index 4ce960438806..e6667a28c014 100644
--- a/lib/slub_kunit.c
+++ b/lib/slub_kunit.c
@@ -140,7 +140,7 @@ static void test_kmalloc_redzone_access(struct kunit *test)
 {
 	struct kmem_cache *s = test_kmem_cache_create("TestSlub_RZ_kmalloc", 32,
 				SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE);
-	u8 *p = kmalloc_trace(s, GFP_KERNEL, 18);
+	u8 *p = __kmalloc_cache_noprof(s, GFP_KERNEL, 18);
 
 	kasan_disable_current();
 
diff --git a/mm/slub.c b/mm/slub.c
index 0809760cf789..95e0a3332c44 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4053,7 +4053,7 @@ EXPORT_SYMBOL(kmem_cache_alloc_node_noprof);
  * directly to the page allocator. We use __GFP_COMP, because we will need to
  * know the allocation order to free the pages properly in kfree.
  */
-static void *__kmalloc_large_node(size_t size, gfp_t flags, int node)
+static void *___kmalloc_large_node(size_t size, gfp_t flags, int node)
 {
 	struct folio *folio;
 	void *ptr = NULL;
@@ -4078,25 +4078,25 @@ static void *__kmalloc_large_node(size_t size, gfp_t flags, int node)
 	return ptr;
 }
 
-void *kmalloc_large_noprof(size_t size, gfp_t flags)
+void *__kmalloc_large_noprof(size_t size, gfp_t flags)
 {
-	void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE);
+	void *ret = ___kmalloc_large_node(size, flags, NUMA_NO_NODE);
 
 	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
 		      flags, NUMA_NO_NODE);
 	return ret;
 }
-EXPORT_SYMBOL(kmalloc_large_noprof);
+EXPORT_SYMBOL(__kmalloc_large_noprof);
 
-void *kmalloc_large_node_noprof(size_t size, gfp_t flags, int node)
+void *__kmalloc_large_node_noprof(size_t size, gfp_t flags, int node)
 {
-	void *ret = __kmalloc_large_node(size, flags, node);
+	void *ret = ___kmalloc_large_node(size, flags, node);
 
 	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
 		      flags, node);
 	return ret;
 }
-EXPORT_SYMBOL(kmalloc_large_node_noprof);
+EXPORT_SYMBOL(__kmalloc_large_node_noprof);
 
 static __always_inline
 void *__do_kmalloc_node(size_t size, gfp_t flags, int node,
@@ -4106,7 +4106,7 @@ void *__do_kmalloc_node(size_t size, gfp_t flags, int node,
 	void *ret;
 
 	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
-		ret = __kmalloc_large_node(size, flags, node);
+		ret = __kmalloc_large_node_noprof(size, flags, node);
 		trace_kmalloc(caller, ret, size,
 			      PAGE_SIZE << get_order(size), flags, node);
 		return ret;
@@ -4142,7 +4142,7 @@ void *kmalloc_node_track_caller_noprof(size_t size, gfp_t flags,
 }
 EXPORT_SYMBOL(kmalloc_node_track_caller_noprof);
 
-void *kmalloc_trace_noprof(struct kmem_cache *s, gfp_t gfpflags, size_t size)
+void *__kmalloc_cache_noprof(struct kmem_cache *s, gfp_t gfpflags, size_t size)
 {
 	void *ret = slab_alloc_node(s, NULL, gfpflags, NUMA_NO_NODE,
 					    _RET_IP_, size);
@@ -4152,10 +4152,10 @@ void *kmalloc_trace_noprof(struct kmem_cache *s, gfp_t gfpflags, size_t size)
 	ret = kasan_kmalloc(s, ret, size, gfpflags);
 	return ret;
 }
-EXPORT_SYMBOL(kmalloc_trace_noprof);
+EXPORT_SYMBOL(__kmalloc_cache_noprof);
 
-void *kmalloc_node_trace_noprof(struct kmem_cache *s, gfp_t gfpflags,
-			 int node, size_t size)
+void *__kmalloc_cache_node_noprof(struct kmem_cache *s, gfp_t gfpflags,
+				  int node, size_t size)
 {
 	void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, size);
 
@@ -4164,7 +4164,7 @@ void *kmalloc_node_trace_noprof(struct kmem_cache *s, gfp_t gfpflags,
 	ret = kasan_kmalloc(s, ret, size, gfpflags);
 	return ret;
 }
-EXPORT_SYMBOL(kmalloc_node_trace_noprof);
+EXPORT_SYMBOL(__kmalloc_cache_node_noprof);
 
 static noinline void free_to_partial_list(
 	struct kmem_cache *s, struct slab *slab,
-- 
2.45.1